app/dashboard/lib/build_status_widget.dart

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:lib.widgets.dart/model.dart';
import 'package:lib.widgets/widgets.dart';

import 'build_status_model.dart';
import 'enums.dart';

/// Displays a build status using its ancestor [BuildStatusModel].
class BuildStatusWidget extends StatefulWidget {
  /// Called then the widget is tapped.
  final VoidCallback onTap;

  /// Constructor.
  const BuildStatusWidget({this.onTap});

  @override
  _BuildStatusWidgetState createState() => new _BuildStatusWidgetState();
}

class _BuildStatusWidgetState extends State<BuildStatusWidget> {
  Timer _timer;
  double _height;

  @override
  void initState() {
    super.initState();
    _timer = new Timer.periodic(
      const Duration(minutes: 1),
      (_) => setState(() {}),
    );
  }

  @override
  void dispose() {
    super.dispose();
    _timer?.cancel();
    _timer = null;
  }

  @override
  Widget build(BuildContext context) {
    return new ScopedModelDescendant<BuildStatusModel>(
      builder: (BuildContext context, Widget child, BuildStatusModel model) {
        _height = model.buildStatusSize.height;
        final backgroundColor = _colorFromBuildStatus(model);
        final hasError = model.errorMessage?.isNotEmpty ?? false;
        final columnChildren = <Widget>[
          new Text(
            model.type,
            textAlign: TextAlign.center,
            style: hasError
                ? _getUnimportantStyle(backgroundColor)
                    .copyWith(fontSize: _errorFontSize)
                : _getUnimportantStyle(backgroundColor),
          ),
          new Container(height: 4.0),
          new Text(
            model.name,
            textAlign: TextAlign.center,
            style: hasError
                ? _getImportantStyle(backgroundColor)
                    .copyWith(fontSize: _errorFontSize)
                : _getImportantStyle(backgroundColor),
          ),
        ];
        if (hasError) {
          columnChildren.addAll(<Widget>[
            new Container(height: 4.0),
            new Text(
              model.errorMessage,
              textAlign: TextAlign.left,
              style: _errorStyle,
            ),
          ]);
        }

        List<Widget> stackChildren = <Widget>[
          new Center(
            child: new Column(
              mainAxisSize: MainAxisSize.min,
              children: columnChildren,
            ),
          ),
        ];

        if (model.lastRefreshEnded == null) {
          stackChildren.add(
            new Align(
              alignment: FractionalOffset.bottomCenter,
              child: new Container(
                margin: const EdgeInsets.only(bottom: 8.0),
                width: 16.0,
                height: 16.0,
                child: const FuchsiaSpinner(),
              ),
            ),
          );
        }

        stackChildren.add(
          new Align(
            alignment: FractionalOffset.topLeft,
            child: new Container(
              margin: const EdgeInsets.only(top: 8.0),
              child: new Text(
                _statusTextFromBuildStatus(model),
                style: _getStatusStyle(backgroundColor),
              ),
            ),
          ),
        );

        return new Material(
          color: backgroundColor,
          child: new InkWell(
            onTap: () => widget.onTap?.call(),
            child: new Container(
              padding: const EdgeInsets.symmetric(horizontal: 8.0),
              child: new Stack(
                fit: StackFit.passthrough,
                children: stackChildren,
              ),
            ),
          ),
        );
      },
    );
  }

  Color _colorFromBuildStatus(BuildStatusModel model) {
    if (model.buildResult == BuildResultEnum.success) {
      return model.successColor;
    } else if (model.buildResult == BuildResultEnum.failure) {
      return model.failColor;
    } else {
      return Colors.grey[300];
    }
  }

  String _statusTextFromBuildStatus(BuildStatusModel model) {
    if (model.buildResult == BuildResultEnum.success) {
      return '\u{1F44D}';
    } else if (model.buildResult == BuildResultEnum.failure) {
      return '\u{1F44E}';
    } else {
      return '\u{1F937}';
    }
  }

  Color _getTextColor(Color backgroundColor) {
    // See http://www.w3.org/TR/AERT#color-contrast for the details of this
    // algorithm.
    int brightness = (((backgroundColor.red * 299) +
                (backgroundColor.green * 587) +
                (backgroundColor.blue * 114)) /
            1000)
        .round();

    return (brightness > 125) ? Colors.black : Colors.white;
  }

  double get _fontSize => _height / 6.0;
  double get _errorFontSize => _height / 10.0;
  double get _statusFontSize => _height / 6.0;
  TextStyle _getImportantStyle(Color backgroundColor) => new TextStyle(
        color: _getTextColor(backgroundColor),
        fontSize: _fontSize,
        fontWeight: FontWeight.w500,
      );

  TextStyle _getUnimportantStyle(Color backgroundColor) =>
      _getImportantStyle(backgroundColor).copyWith(
        fontWeight: FontWeight.w300,
      );

  TextStyle get _errorStyle => new TextStyle(
        color: Colors.red[900],
        fontWeight: FontWeight.w900,
        fontSize: _errorFontSize,
      );

  TextStyle _getStatusStyle(Color backgroundColor) =>
      _getImportantStyle(backgroundColor).copyWith(
        fontSize: _statusFontSize,
      );
}